1. Field of the Invention
The present invention relates to a key switch device, and more particularly, to a key switch device suitable for use on a keyboard to be used as various input devices of a personal computer, word processor, etc.
2. Description of Related Art
A conventional key switch device (not shown) is provided with a vertically movable key top in the upper position and supported at the underside with a supporting member assembled in a criss-cross fashion.
Below the key top a metal plate is disposed; on the upper surface of the metal plate, a membrane sheet is placed. A rubber spring is interposed between the membrane sheet and the key top.
With the depressing and releasing operation of the key top, the key top is moved up and down between the upper and lower positions by the elastic force of the rubber spring. When the key top is in the lower position, the switching portion of the membrane switch is turned on by the rubber spring.
The conventional key switch device stated above is adopted in a portable equipment such as a notebook PC. With a recent rapid trend of downsizing portable equipment, there has been a keen demand for a low-profile key switch device.
To meet the demand for a low-profile conventional key switch device (not shown), therefore, the metal plate for attaching the membrane switch has been decreased in thickness and the key top has been reduced in thickness to a minimum.
In the conventional key switch device described above, since the key top is decreased in thickness to about 2 mm to meet the demand for reduction in thickness, there arises such a disadvantage that the key top has no three-dimensional appearance, being deteriorated in appearance.